Street lighting luminaire



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ATTORNEY Patented June 28, 1949 STREET LIGHTING LUMINAIRE Thomas W.Rolph, Newark, Ohio, assignor. t Holophane Company, Inc., New York, N.Y., a corporation of Delaware Application December 18, 1945, Serial No.635,698

Claims. 1

The present invention relates to street lighting 'luminaires and is moreparticularly directed toward such luminaires provided with globesunderneath the light source.

A common form of street lighting luminaire employs adownwardly actingreflector with a cut-off angle approximately horizontal and having acontour to reflect most of the light out below the mouth of thereflector at angles high enough above the nadir to fall on remote areasof the street. Such reflectors are customarllygclosed by globes, theseglobes generally being provided with external vertical difl'usingflutes'whichbreak-up the light rays. Such globes may also be providedwith vertical prismatic forms designed to give various asymmetricdistributions for employment at various locations along the street.

The type of reflector globestreet lighting luminaire just referred to ischaracterized by very high brightness in the region Just below thehorizontal where the dominant light rays are reflected out at highangles for lighting remote street areas and below this band of highbrightness the globe when viewed from remote points of observation, hasvery low brightness, the reason being that the lower part of the globetransmits the light at angles substantially below the dominant beam.

The present invention contemplates providing the globes of streetlighting luminaires of the type above referred to, with suitable lightrefracting elements to elevate some of the light which would normallyfall on the nearer areas of the street and emit it into the same generaldirection above the nadir as the dominant beam. Inthis way the lowerpart of the globe normally so dimly lighted as to appear dark, is nowlighted up with suflicient brightness. to appear bright alongside thevery high brightness obtained at the top of the globe.

The accompanying drawings show, for purposes of illustrating the presentinvention, an embodiment in which the invention may take form, it beingunderstood that the drawings are illustrative of the invention ratherthan limiting the same.

In these drawings:

Figure 1 is a diagrammatic sectional view through a prior art type ofluminaire;

Figure 2 is an elevational view of such a luminaire as it appears from aremote point of observation;

Figure 3 is a top plan view of a globe in the form of a refractordesigned for mounting at the side of the street;

Figure 4 is a side elevational view of the refractor of Figure 3 withparts in section on the line 4-4;

Figure 5 is a fragmentary sectional view on the line 5-5 of Figure 3;and

Figure 6 is a fragmentary sectional view on the line 66 of Figure 5. c

In Figure 1 the prior art type of luminaire is illustrated as employinga pendent incandescent lamp ill with the light center at L. C., adownwardly acting reflector II and an enclosing globe 12. The lower partof the reflector l I is parabolic and is designed to send out thereflected light rays illustrated at l3 at the desired angle, typically75 above the nadir. Most of the light flux emitted by the filament istransmitted, however, in this reflected beam or in a beam of directlight rays at high angles above the nadir. Some of the flux, however,such as represented by rays l4 emitted directly from the lamp, passesout at such low angles as to fall on nearby street areas.

Such prior art globes are customarily provided with. external difiusingribbing such as illustrated at [5 (Figures 4 and 6), this ribbingextending the full depth of the globeand serving to spread rays such asl3 and I4 laterally to a slight extent. If desired, the region of theglobe through which the rays H are transmitted may be provided withinternal prismatic configurations to provide asymmetric distributions.When such a globe is viewed from a. remote street area it has a, verybright zone at the top, as indicated in Figure 2 and a dark orrelatively dark zone at the bottom, as also indicated in this figure.

The new globe is intended for employment with a reflector such as Habove referred to. In the particular form shown this globe is what ismore generally known as a lateral refractor. It has vertical prisms forthe full depth of the refractor occupying a lateral zone somewhat lessthan as indicated at 20. This vertical prism system extends all the wayaround the upper part of the refractor as indicated at 2| and thesevertical prisms control most of the light flux emitted by the unit andsend it along the street in a well known manner, the rays beingindicated at 22, On each side of the zone of full depth vertical prisms,the refractor is provided with a zone 23 occupied by light elevatingannular prisms such as indicated at 24 in Figure 5. These lightelevating prisms are preferably spaced apart as indicated in this figureso that regions 25 are provided for direct light rays to pass throughthe refractor, such direct rays being indicated at 26. The annularprisms 24 act on light rays 21 and 3 elevate them as indicated at 28 sothat they are transmitted at substantially the same angle above thehorizontal as the tight rays 22. The

light rays 26 and 28 pass through the difiusing flutes l5 and are spreadas indicated in Figure 6. Thus the observer at the remote point not onlyreceives light rays from the upper zone of the refractor, but also fromthe lower zone so that this lower zone instead of appearing dark is nowwell lighted up.

While the application of the invention illustrated in Figure 3 shows itas employed in a street lighting refractor for mounting on the side ofthe street, it will be understood that the light elevating prisms placedon the globe to be viewed lengthwise of the street, may be employed withsymmetric globes or various forms of asymmetric refractors.

Since it is obvious that the invention may be embodied in other formsand constructions within the scope of the claims, I wish it to beunderstood that the particular form shown is but one of these forms, andvarious modifications and changes being possible, I do not otherwiselimit myself in any way with respect thereto.

What is claimed is:

1. The improvement in street lighting luminaires having a pendentconcentrated light source, a downwardly acting annular reflector aboutthe source with its mouth at substantially the level of the source andhaving a contour in the region immediately above the horizontal planethrough the source which directs reflected light rays across theluminaire axis at high angles above the nadir in a narrow region belowthe mouth of the reflector, and a bowl shaped globe fitted across themouth of the reflector and having an upper zone for transmitting thesaid reflected rays and higher angled direct light toward remote streetareas without vertical deviation and a lower region for intercepting andtransmitting direct light rays below the higher angled direct light,which improvement comprises a vertically disposed series of horizontalprisms in the lower region of the globe of variant refracting power toelevate the light emitted by them into substantial parallelism with thereflected rays transmitted by the upper part of the bowl whereby theentire bowl, when viewed from regions into which the dominant reflectedlight is directed, is luminous.

2. The improvement of claim 1, wherein the horizontal prisms areseparated from one another so that a portion of the direct light passesthrough the globe without vertical deviation.

3. A street lighting luminaire comprising a concentrated light source, areflector about the light source with its mouth at substantially thelevel of the light source for reflecting light across the luminaire axisat high angles above the nadir for lighting distant street areas, alight transmitting globe through which said light passes, the globecarrying, in the region below that through which the reflected lightpasses, a series of interiorly disposed vertically spaced prisms whichelevate portions only of the light into general parallelism with thereflected rays, while allowing the light received between the prisms topass through the globe without vertical deviation, and on its outersurface minor horizontal curvatures which provide a degree of lateralspread to the transmitted light.

4. A street lighting luminaire as claimed in claim 3, wherein the globehas vertical light concentrating prisms for redistributing the reflectedlight laterally into beams, and the prisms occupy a relatively narrowsector on each side of the beam axis.

5. A street lighting refractor in the form of a bowl with downwardly andinwardly extending side walls, the upper part of the side walls havingsystems of vertical light concentrating prisms, the lower parts of thewalls below the central portion of each system of prisms having avertically disposed series of horizontal prisms of variant retractingpower which elevate downwardly divergent light rays into parallelism.

THOMAS W. ROLPH.

REFERENCES CITED The followingreferemces are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 805,742 Mygatt Nov. 28, 19051,674,165 Dorey June 19, 1928 2,099,034 Rolph Nov. 16, 1937 2,110,018Halvorson Mar. 1, 1938 2,260,693 Rolph Oct. 28, 1941

